T-shaped obelisks, one of the most known features of Gˆbekli Tepe, were obtained from stone quarries located on the limestone plateau near the site using stone and bone tools. They were then placed in stone walls made of local limestone, where they were moved and / or easily accessible. The structures seen today in Gˆbekli Tepe are not the first buildings in the area. What we see today in the excavation area is the result of construction activities, construction of new buildings and covering of buildings over 1400 years. In this period, the walls and obelisks in the structures were removed from their original place for reuse in the same or another structure. Today, we can call this process írecycling G¸n¸m¸zde.
To date, nine monumental round-oval structures have been excavated and these structures have been named from A to H (Figure 3). These round-oval structures are generally discovered in lower-lying depression areas, so they must be the oldest structures in the area and some of them have been used for centuries. In addition to large monumental structures, a smaller number of rectangular structures were found. These quadrangular structures are located in the high parts of the hill and on the slopes, and are dated to the time the site was last used (EPPNB). Compared to the monolithic round-oval structures, the quadrangular structures have smaller T-shaped obelisks and these obelisks are placed in low walls or walls.